6 x 6 sounds pretty small to me. SkySlab is a tin shed 2.7 x 1.8 but I have a flat roof which swivels 90* to open to the sky. Mine has just enough room if you are careful to move around the scope (10" Serrurier Truss Newt on EQ6) with a PC desk etc along one of the short sides.
Do you intend to be in the shed while in use ? If so you will be very restricted. Some photos of my setup on
http://www.iceinspace.com.au/forum/s...ad.php?t=88712 Scroll down to about May for open roof shots with 10" on the EQ6.